Using Satellite Communications for a Mobile Computer Network
by
Douglas J. Wyman
Washington State Patrol
Telecommunications Division
The Washington State Patrol (W.S.P.), in response to the need for Patrol Car Automation
has developed a prototype Mobile Computer Network. The network uses "off the shelf"
hardware to provide a file passing network environment for notebook computers in
vehicles. This network links the officers with the W.S.P.'s information system,
other Washington state agencies and the National Law Enforcement Telecommunications
System. The system provides direct links for messaging and inquiry between the Patrol
cars, every state and the Canadian Provinces.
The information to be presented includes; The current requirements of Patrol Car
Automation systems, the targets of the WSP design, information on the hardware and
software used in the system as implemented in the prototype and the future goals
for and visions of the future of Patrol Car Automation.
Most currently available commercial systems for Patrol Car Automation are mobile
data terminal systems that limit agencies to specific manufacturers of equipment.
The currently available systems do not easily allow for links to disparate information
systems nor is the implementation of new processes or functions easily accommodated.
The W.S.P. needed a system that incorporated a removable notebook computer. The
system would have to enhance the officer's effectiveness by reducing the amount
of information that the voice radio network was required to pass. The W.S.P. needed
a system based on the existing microwave and UHF radio system for data communications
but portions of the mobile network had to be immune from terrestrial disasters due
to the state's location on the Pacific earthquake zone and the threat of volcanic
disturbance.
The Patrol's solution was the design of a Mobile Computer Network (MCN) that includes
Mobile Satellite Communications. The hub of the network is designed around Imbedded
Process Servers (IPS) linked on a token ring LAN. Each IPS operates in a client/server
mode serving both network users and other IPS's. The mobile nodes on the network
use background software that transfers all files deposited on the "network" directory
back to the hub. Those files carry a header designating destination, originator
and other necessary information. The media location of the destination is transparent
to the users. That destination can be on the UHF system, the physical LAN, the Patrol's
SNA WAN or the satellite system.
Currently, the Patrol officers have available all routine law enforcement query
functions, a store and forward E-Mail function and outbound FAX from the car. Experiments
have been done with image transmission, voice interface and mobile docking ports.
The direct benefits to the citizens of the state are the increase of stolen recoveries,
quicker apprehension of wanted persons, reducing the delay for violators, greater
recovery of fines and crime deterrence.
Incorporating satellite radio communications into the Mobile Computer Network has
the additional benefit of providing a communications link that is virtually immune
to terrestrial disaster. The Washington State Patrol intends on allocating enough
Satellite based mobiles to provide backup for the major public safety communications
centers in the state.